Influence of Copper Atomic Fraction on the Mechanical Properties of FeNiCrCoCu x High⁃Entropy Alloys at High Temperature

This study systematically investigates the effects of the Cu atomic fraction on the mechanical properties and microscopic deformation mechanisms of FeNiCrCoCuₓ high⁃entropy alloys at 1 000 K using molecular dynamics simulations. The results show that, as the Cu atomic fraction increases, the yield stress decreases from 5.61 GPa to 4.99 GPa and Young's modulus decreases from 70.85 GPa to 53.86 GPa. In contrast, the fraction of atoms transformed from face⁃centered cubic (FCC) to hexagonal close⁃packed (HCP) structures decreases, while the frequency of dynamic recrystallization (DRX) increases significantly. The dislocation density is reduced, lattice distortion is relaxed, and the stress distribution becomes more uniform. Further analysis confirms that Cu addition lowers the stacking⁃fault energy and accelerates DRX, thereby markedly improving ductility without compromising high⁃temperature stability. These findings provide an atomic⁃scale theoretical basis for designing novel high⁃entropy alloys with both high strength and toughness and excellent heat resistance.